DNA is the hereditary material, which is identical in
all cells of our body. A gene is a DNA fragment or a ‘building block’ that acts
as instructions to make proteins. Human genome contains approximately 20,000 to
25,000 genes. Genes contain information about where and when to produce
necessary proteins and they also determine the protein composition, which lays
ground to difference in protein structure and function and thus entire
functionality of the body.

DNA consists of nucleotides (A, T, C, and G) and DNA
fragments of two different individuals may contain a difference in a single
nucleotide, e.g. GCCTGA and GCTTGA, respectively. Such differences
arise from SNPs (pronounced snips) or
single nucleotide polymorphisms or variations in DNA sequence. SNPs occur on
average once in every 1000 nucleotides and their differences are responsible
for genetic uniqueness of every individual (except for identical twins who
share the same genotype). Thus, SNPs account for approximately 90% of the
genetic differences between individuals (Brookes, 1999). Each human cell has two
copies of chromosomes and thus we receive from our parents either two different
or two identical copies of each SNP.

SNPs do not generally cause diseases, but they may
help to determine the probability of developing an illness. Such DNA sequence
variations may also determine individual response to pathogens, chemicals,
drugs, vaccines, and also to various nutrients (e.g. whether weight gain is
more likely in case of excessive consumption of carbohydrates), and the amount
of physical exercise required to maintain normal weight or to become a
successful athlete.

FTO gene has shown the strongest association with
the occurrence of overweight and obesity (Scuteri, Sannaet
al.2007; Speliotes, Willeret al.
2010). FTO also participates in
regulation of appetite and satiety. People with risk alleles in FTO gene are at
70% higher risk of becoming overweight in comparison to those without risk
alleles. Occurrence of one risk allele increases the risk of becoming
overweight by 30%.

MC4R gene and FTO gene regulate the mechanism behind hunger
and satiety. MC4R collects the hunger and satiety signals and instructs the
body to either eat or stop eating (Fani, Bak et al.
2013). Satiety does not occur easily in individuals with
risk alleles in MC4R gene and thus, they may overeat and constantly snack
between meals. This may lead to overweight and obesity (Lubrano- Berthelier, Cavazoset al. 2003; Speliotes, Willer et
al. 2010).

FABP2 gene takes part in intracellular fatty acid transportation
to adipocytes and regulates fat uptake in epithelial cells of the small
intestine (Baier, Sacchettiniet
al.1995). Studies have shown that the
presence of risk allele is incidental to increased binding of fatty acids and
is therefore associated with both increased body mass index, body fat percentage,
visceral fat, and excess weight (Baier, Sacchettiniet
al.1995).

PPARG gene plays an important role in adipogenesis (Lowell 1999), lipid metabolism and
breaking down fatty acids. Individuals with risk alleles in PPARG gene are more
susceptible to fatty food, they find it harder to lose weight and thus, they
are at higher risk of gaining excess weight. When consuming fatty food, PPARG
stores fat and makes small adipocytes to grow in size (Kubota, Terauchiet al.
1999).

In people with risk allele in ADRB2 (II) gene, the fat
burning is not as efficient as in people without relevant risk allele. Additionally,
individuals with risk allele have increased risk of obesity in case of
high-carb diet, which arises from elevated insulin release and changes in breaking
down carbs and fats. Decomposition of carbohydrates increases, while decomposition
of fatty acids reduces significantly and they are stored as body fat (Martinezet al. 2003).

ADRB3 is located on the surface of abdominal cavity
and brown fat cells, stimulating lipolysis and thermogenesis by releasing noradrenaline
when subject to low temperature, eating, and exercise (Tappy 1996). The impact of ADRB3 gene
on obesity depends on the level of physical activity. The presence of risk
alleles in ADRB3 causes reduced lipolysis in fat cells (Umekawa, Yoshidaet
al. 1999). Thus, the occurrence of ADRB3 risk
alleles may lead to obesity due to reduced energy consumption in adipose tissue.
Individuals with risk alleles have increased BMI in case of sedentary
lifestyle. To reduce the risk of excess weight, people with risk alleles are
recommended to be physically active for more than 10 active hours a week.
People with A allele lose weight more easily and even lower physical activity
is enough to lower the risk of overweight.

IGF1 is expressed locally in many tissues including muscle cells and is a major regulator of muscle mass during development, due to its effect on myogenic cell proliferation and differentiation (Schiaffino and Mammucari 2011).

T allele in NOS3 gene indicates predisposition towards
achieving better results in power sports (Gómez-Gallegoet al.
2009). Nitric oxide is a gas
produced in the body, required for “communication” between the cells, relaxation
of blood vessels, and supplying muscles and skin with blood. Nitric oxide has
an important role in healing and regeneration of the myocardial tissue (Otani 2009). Regular exercise increases
NO production, thus also improving the performance capacity. Regulation of
blood supply is particularly important for athletes engaged in high-endurance
sports, because training a muscle requires additional oxygen.

Latest blog posts

Hypersensitivity
or intolerance against certain foods continues to be controversial
topic. What is the mechanism behind it, whether and how to determine
it, how to proceed after receiving test results?

Have you felt more forgetful and less focused after a sleepless night?
Have you noticed that some of your friends are active already early
in the morning, while others would sleep till noon and prefer to work
late at night? These are but a few examples of the effect sleep may
have on us, our productivity and even our health.

Sports Gene helped junior swimmer Kregor Zirk to determine his athletic predisposition and food intolerance. On 11 May, daily newspaper Postimees published an article that discusses in detail the expectations of Kregor and his coach Kaja Haljaste regarding the genetic test and practical use of the results in planning Kregor’s future career.